Method and apparatus for network bandwidth conservation

ABSTRACT

Methods and apparatus for conserving bandwidth within a network based on two or more different service levels. In an exemplary embodiment, programming that is simulcast on two or more program channels is mapped to one physical channel during periods when the programming is scheduled at only one service level (e.g., standard definition), thereby conserving bandwidth on the network that would otherwise be consumed by the simultaneous broadcast on the two or more channels. When the programming service level becomes heterogeneous across the channels (e.g., SD and HD simulcast), physical channel(s) supporting the HD content are provided within a local service area only “on-demand” using, for example, a switched digital channel allocation. Accordingly, no HD broadcast occurs within a given area until at least one user requests it, thereby further conserving network bandwidth.

BACKGROUND OF THE INVENTION

1. Field of Invention

The present invention relates generally to the field of networkbandwidth utilization, and specifically in one aspect to conservingavailable bandwidth on the network to support video services (such ashigh definition or HD video) over a content-based network such as acable television network.

2. Description of Related Technology

One significant competitive challenge presently faced by networkoperators relates to managing and conserving bandwidth. This includesthe reclamation of otherwise under-utilized or unused bandwidth suchthat the service and/or customer base can be expanded withoutsignificant modifications or build-outs of the underlying networkinfrastructure. For example, it is clearly desirable to expand the typesand availability of “next-generation” network services, includinghigh-definition (HD) broadcast, VOD, high-speed data, VoIP, InteractiveTV, etc. over time, without the need for major capital expenditures orsystem modifications. Hence, network operators are increasingly focusedon techniques for “squeezing” as much capacity out of their existingnetworks as possible.

Driving the foregoing expansion of services are several other relatedfactors, such as the increased adoption of HD televisions by consumers(especially as their price continues to decline), and the increasedprevalence of HD content provided by non-cable service providers. Suchservice providers may comprise, e.g., satellite direct broadcast (DBS)networks, stand-alone HD services such as VOOM^(sm), so-called“over-the-air” HD broadcast systems, and even high-speed InternetProtocol (IP) or similar networks (whether via DSL, cable modem, orotherwise), often referred to as “IPTV”. These factors place addedemphasis on the cable operator's efficient use their existinginfrastructure and its finite bandwidth.

In most cable networks, programs are transmitted using MPEG (e.g.,MPEG-2) audio/video compression. Since cable signals are transmittedusing Quadrature Amplitude Modulation (QAM) scheme, available payloadbitrate for typical modulation rates (QAM-256) used on HFC systems isroughly 38 Mbps. In many deployments, a typical rate of 3.75 Mbps isused to send one video program at resolution and quality equivalent toNTSC broadcast signals. In digital television terminology, this iscalled Standard Definition (SD) television resolution or service.Therefore, use of MPEG-2 and QAM modulation enables carriage of 10 SDsessions on one RF channel (10×3.75=37.5 Mbps<38 Mbps).

Entertainment-quality transmission of HD signals requires about fourtimes as much bandwidth as SD. For an exemplary MPEG-2 Main Profile—HighLevel (MP@HL) video compression, each HD program requires approximately15 Mbps bitrate. Although revenues from HD services and programming maynot be four times the revenue from SD service, the ability to offer HDis often critical to cable operators' strategy to be a leader in digitaltelevision service offerings.

In the context of a cable network, present day infrastructure providescapacity up to approximately 750 Mhz (with a lesser number of networksbeing built out to approximately 870 Mhz). As noted above, the bandwidthrequirements associated with the aforementioned HD and othernext-generation services (even when implementing complementarynext-generation video and audio compression algorithms) are very highcompared to existing content payloads and services such as standarddefinition (SD) television.

However, in the short term, even the most optimistic projections for thedemand of HD and other such next-generation services would not requireall (or even the majority) of the total available capacity of a giveninfrastructure. Stated differently, many “low-bandwidth”, standarddefinition (SD) users and providers will exist for years to come. Forexample, most HD content presently offered is restricted to “prime time”programming, as well as certain sporting events, movies, and otherspecialized programming; this leaves a large pool of non-HD programmingwhich must also be efficiently supported. Hence, one present goal forthe MSO is to manage such heterogeneous (i.e., SD and HD) environmentsas efficiently as possible.

In U.S. cable systems, downstream RF channels used for transmission eachoccupy a 6 MHz spectral slot in the available bandwidth (i.e., betweenapproximately 54 MHz and 870 MHz). As previously noted, deployments ofthe next-generation services (e.g., VOD, HD broadcast/simulcast,PVR/DVR) have to share this spectrum with already established analog anddigital cable television services including SD broadcasts. For thisreason, the exact RF channel used for a given service may differ fromplant to plant. However, within a given cable plant, all homes that areelectrically connected to the same cable feed running through aneighborhood will receive the same downstream signal. For the purpose ofmanaging services, these homes are grouped into logical aggregations orclusters typically called Service Groups. Homes belonging to the sameService Group receive their services (e.g., broadcast or VOD service) onthe same set of RF channels.

Broadcast programs within the cable network may be unicast (i.e.,transmitted within a multiplex on one carrier or QAM and an associatedprogram channel), or multicast (i.e., transmitted over two or more QAMs,each associated with a different program channel). During certainperiods, an SD version of a program will be broadcast on one channel,and the HD counterpart thereof broadcast a second channel (SD/HDsimulcast). During other periods, the SD version of a program will bebroadcast on both channels (SD/SD simulcast).

On-demand service such as VOD is typically offered over a given number(e.g., 4) of RF channels from the available spectrum. Thus, an ODService Group consists of homes receiving OD signals over the same 4 RFchannels. Reasons for this grouping include (i) that it lends itself toa desirable “symmetry of two” design of products (e.g. ScientificAtlanta's MQAM), and (ii) a simple mapping from incoming AsynchronousSerial Interface (ASI) payload rate of 213 Mbps to four QAM payloadrates.

From the discussion above, the need for allocation of the bandwidthwithin the network is evident. One such prior art function, called aService Resource Manager (SRM), is used for allocating bandwidth basedon OD session requests. When a new session (e.g., VOD) request is made,the SRM receives that request, allocates bandwidth on a downstream QAMchannel, and sends the information back to the CPE that made the requestso that it can tune to the right RF channel and the program therein.Since the SRM controls mapping of incoming session requests to QAMchannels within the Service Group, it is an appropriate place for aCable Operator to enforce RF channel usage policy. In general, the SRMshould maximize availability of bandwidth to OD and other sessions (byefficiently recycling bandwidth from expired sessions) and by ensuringsome level of redundancy in case of equipment failure (e.g. a QAMmodulator goes down). The SRM function can be implemented at the edge orcore of the network, in a VOD server, or elsewhere. Depending on wherethis function is implemented, it is variously referred to as NSG(Network Services Gateway) and SRM (Service Resource Manager).

For example, in a Scientific Atlanta network, the VOD server acts as theservice resource manager and asks the Digital Network Control System(DNCS) for specific resources. The DNCS responds with a negative orpositive response to the request and the VOD server implements theappropriate logic based on the response.

The SeaChange MediaCluster Server device manufactured by SeaChangeInternational Corporation comprises a group of fault-resilient VODservers connected over a network, in effect acting as one server. See,e.g., U.S. Pat. No. 5,862,312 to Mann, et al. issued Jan. 19, 1999 andentitled “Loosely coupled mass storage computer cluster” and itsprogeny. The SeaChange apparatus further includes a session resourcemanager (SRM), and associated connection manager (CM) and streamingservice (SS). The CM ostensibly allocates bandwidth, selecting the bestnetwork delivery path over which to stream data to the requestingentity. The SS “optimizes” bandwidth and provides some level offail-over behavior, such that software component failure will notnecessarily cause loss or tear-down of the underlying sessions. Nofunctionality relating to the selective conservation of bandwidth basedon different service levels (e.g., SD or HD) is provided within thisapparatus, however.

While useful for OD session allocation, the SRM function present inmodern cable networks does not provide an adequate mechanism toselectively allocate bandwidth (or more importantly conserve bandwidth)for broadcasts based on their service level, e.g., SD or HD.Furthermore, no adequate mechanism for eliminating the redundancy withinthe aforementioned SD/SD simulcast paradigm is provided by the SRM, orfor that matter any other prior art solution.

Various other schemes for resource and bandwidth management within acable network are known. For example, U.S. Pat. No. 4,521,881 toStapleford, et al. issued Jun. 4, 1985 and entitled “Data communicationsystem with increased effective bandwidth” discloses a broadband datacommunication system that provides increased bandwidth for thetransmission of electrical information signals over a coaxial cablehaving main receive and transmit branches, and having drop line pairsconnected to the main branches at junction points. A plurality of userdevices are connected to each drop line pair, including a particular setconnected to a particular pair. Each user device of the set can transmitand receive signals of local frequencies in a selected bandwidth.Frequency isolation means is connected to the particular drop line pairadjacent its junction point, and passes signals of the local frequenciesonly from the transmit drop line to the receive drop line, whileblocking signals of the local frequencies from transmission over themain cable branches. The particular set of user devices and the filterisolation means together define a subnet. Other subnets can use the samebandwidth of local frequencies without interference, thereby increasingthe effective bandwidth of the system.

U.S. Pat. No. 5,963,844 to Dail issued Oct. 5, 1999 entitled “Hybridfiber-coax system having at least one digital fiber node and increasedupstream bandwidth” discloses a method and apparatus for increasingupstream bandwidth and reducing ingress noise in a shared hybridfiber-coax transmission system. The method comprises modulating at leasta portion of upstream signals received from subscribers to a highfrequency band (e.g., 750-1000 MHz), thereby increasing the upstreambandwidth. The high frequency upstream signals are then digitallyregenerated in the coaxial cable plant prior to receipt at a fiber node.At the fiber node, the high-frequency upstream signals are againdigitally regenerated and are then transmitted optically in a basebanddigital format between the fiber node and a head end. The digitalregeneration of the high frequency upstream signals, and the opticaltransmission of such signals in a baseband digital format reduces theincidence of ingress noise.

U.S. Pat. No. 6,124,878 to Adams, et al. issued Sep. 26, 2000 entitled“Optimum bandwidth utilization in a shared cable system data channel”discloses a full service network (FSN) providing three communicationchannels that end between a headend and each set-top within the FSN.These channels comprise (1) forward-application-transport (FAT) channelsthat supply data from the headend to all or to only addressed ones ofthe set-tops, (2) a forward-data-channel (FDC) that supplies data fromthe headend to all or to only addressed set-tops, and (3) areverse-data-channel (RDC) that supplies data from the set-tops to theheadend. A fixed bandwidth FDC provides a first bandwidth portion forthe high priority transmission of certain types of items at a continuousbit rate (CBR). All other items are transmitted over the FDC using at anavailable bit rate (ABR). A priority system for the selectivetransmission of these other items is based upon (1) how full a databuffer for an item is, as compared to a fullness reference, (2) how oldthe oldest data in the data buffer for the item is, as compared to anage reference. The fullness reference and the age reference are usuallydifferent for each of these other data items.

U.S. Pat. No. 6,169,728 to Perreault, et al. issued Jan. 2, 2001 andentitled “Apparatus and method for spectrum management in a multipointcommunication system” discloses an apparatus and method for spectrummanagement in a cable system that controls upstream channel usage forsecondary stations transmitting information to a primary station anddownstream channel usage for secondary stations receiving informationfrom a primary station. The apparatus and method controls channel loadbalancing, channel congestion, and channel assignment in the cablesystem, and controls upstream channels independently from downstreamchannels. Factors and parameters utilized in such channel control andallocation include error parameters, channel noise parameters, transmitand receive loading factors, and congestion parameters.

U.S. Pat. No. 6,201,901 to Imajima, et al. issued Apr. 3, 2001 andentitled “Video data distributing device by video on demand” discloses amechanism that determines whether or not the broadcast of a requestedvideo is to be provided in a FVOD or a NVOD service, and if there is anyavailable channel (bandwidth) for the broadcast. If the broadcast hasnot been switched from the FVOD service to the NVOD service, then a busystate monitoring mechanism checks the number of the current simultaneoussubscribers for the video. If the number is equal to or larger than athreshold, then the busy state monitoring mechanism instructs an NVODservice providing mechanism to broadcast the requested video in the NVODservice. If the number is smaller than the threshold, then the busystate monitoring mechanism instructs an FVOD service providing mechanismto broadcast the requested video in the FVOD service.

United States Patent Publication No. 20020095684 to St. John, et al.published Jul. 18, 2002 end entitled “Methods, systems and computerprogram products for bandwidth allocation based on throughputguarantees” discloses methods, systems and computer programs forcontrolling access to a shared communication medium such as a cablenetwork utilizing a revolving priority queue. The revolving priorityqueue (RPQ) is divided into at least a low priority tier having aplurality of request queues and a high priority tier having a pluralityof request queues. A request is directed into an initial queue in thehigh priority tier if throughput for an end user associated with therequest fails to meet a guaranteed throughput. Furthermore, bandwidthmay be allocated based on an order in which requests are read from theRPQ, where requests are read from the high priority tier before requestsare read from the low priority tier of queues. Additional systemembodiments are provided which may be used for requests or forpacket-based bandwidth allocation.

United States Patent Publication No. 20020154655 to Gummalla, et al.published Oct. 24, 2002 entitled “System and method for combiningrequests for data bandwidth by a data provider for transmission of dataover an asynchronous communication medium” discloses a method and systemfor combing requests for data bandwidth by a data provider fortransmission of data over an asynchronous communication. A headendreceives one or more bandwidths requests from one or more cable modemsvia upstream communication. A scheduler then combines one or morebandwidths requests from the same cable modem to create a single databurst bandwidth. The headend then grants the data burst bandwidth to theappropriate cable modem via downstream communication.

United States Patent Publication No. 20030140351 to Hoarty, et al,published Jul. 24, 2003 entitled “Cable television system compatiblebandwidth upgrade using embedded digital channels” discloses apparatus,methods, and systems for providing an increase in the effectivebandwidth of a cable television distribution plant in a mannercompatible with most common cable television systems. By using methodsand systems for simultaneously transmitting a standard analog televisionsignal and a digital data signal in a manner that minimizes interferenceof each with the other, one or more data carriers may be embedded withinone or more analog television channels in accordance with variousaspects of the present invention. These combined signals can betransmitted over the existing cable television distribution plant to alocation at or near the subscribers so that, among other things, thatthe subscriber may “pause and resume” much in the way Personal VideoRecorders work.

Various approaches to upstream signaling for session establishment andchannel change within a network are also known in the art. For example,U.S. Pat. No. 6,742,187 to Vogel issued May 25, 2004 and entitled“Upstream bandwidth allocation map (MAP)-initiated channel change methodfor data-over-cable systems” discloses a method by which an upstreamchannel change for a cable modem in a data-over-cable system is achievedvia an upstream bandwidth allocation map message sent from a cable modemtermination system to cable modems, instead of requiring an exchange ofupstream channel change request and reply messages. The result is thatthe upstream channel change can be made essentially immediately, in adeterministic fashion. As such, the upstream channel change method isparticularly useful for time-sensitive applications, such as Internettelephony, VoIP, and Internet video on demand services. Load balancingcan also be achieved more efficiently.

United States Patent Publication No. 20040163109 to Kang, et al.published Aug. 19, 2004 and entitled “Method for controlling networkdigital broadcasting service and system therefore” discloses a method ofservicing requests associated with the broadcasting of SD (Standard)level and HD (High Definition) level content over a network (e.g., aDigital Subscriber Line). The method comprises providing a directrequest (control message) to a digital broadcast server from a clientdevice for a session connection, and establishing a session by receivinga confirmation from the digital broadcasting server. This approachbypasses the SRM (i.e., is direct between the client device and server),thereby ostensibly streamlining the process. Also, a server for achannel change can be requested directly from the client device, thechannel change being completed by receiving a confirmation from theserver. Other direct client-server requests and confirmations includemessages for checking the status of the client device, and for sessiontermination.

While the prior art referenced above (including the SRM function) hasgenerally identified the need for bandwidth management functions andupstream or reverse channel signaling, it fails to provide any apparatusor method that optimizes or conserves bandwidth when bothnext-generation (e.g., HD) and current generation (e.g., SD) content arepresent, especially in the instance of SD/SD and SD/HD simulcasts.Furthermore, the prior art SRMs and algorithms are not flexible withregard to allowing selective implementation of one or more businesspolicies with the network, or even within a single local service area orgroup, and do not leverage efficiencies relating to “switched digital”channel bandwidth allocation for purposes of creating real time HDbroadcast sessions.

Hence, based on the foregoing, there is a distinct need for improvedapparatus and methods that permit the efficient use and conservation ofavailable bandwidth on content-based networks, such that varying degreesof both present-generation (e.g., SD) and-next generation (e.g., HD)services can be easily and reliably provided to the largest possiblecustomer base. Such improved apparatus and methods would ideally (i) beimplemented with only minimal modification to the existinginfrastructure, (ii) allow for longer-term migration to differentservice mixtures (e.g., increased use of HD, VOD, and similar servicesover time), and (iii) allow for dynamic variation of the mixture ofservices as a function of one or more parameters such as time of day,service area, service class, etc., including for example leveraging a“switched digital” system architecture for broadcasting HD content.Mechanisms to implement different types of operational and/or businessrules would also be provided.

SUMMARY OF THE INVENTION

The present invention satisfies the foregoing needs by providingimproved apparatus and methods for network bandwidth conservation andoptimization, such as may be used in a cable or satellite network.

In a first aspect of the invention, an improved method of operating anetwork carrying information to a plurality of users at a first servicelevel is disclosed. In one embodiment, the service level comprises astandard definition (SD) encoding, and the method comprises: schedulingthe information at the first service level onto first and second userchannels of the network simultaneously, at least the first user channelhaving a first physical channel associated therewith; defining arelationship between the first physical channel and the second userchannel; and selectively tuning at least one of the users to only thefirst physical channel in response to the at least one user attemptingto tune to either of the first and second user channels based at leastin part on the relationship. This approach allows for significantconservation of bandwidth on the network during simulcast operations,since only one physical channel (and one broadcast of the SD content) isrequired to service both program channels.

In a second aspect of the invention, an improved method of operating CPEwithin a content-based network is disclosed. In one embodiment, themethod comprises: receiving a plurality of scheduling informationregarding programming to be broadcast, the information identifying afirst period when the programming is scheduled substantiallysimultaneously on first and second program channels; receiving, duringthe first period, user commands to tune to the first or second programchannels; and selectively tuning, based at least in part on theinformation, to a first physical channel irrespective of whether theuser commands the CPE to tune to the first or the second channel.

In another embodiment, the method comprises: receiving a plurality ofmapping information during a first period when programming is scheduledsubstantially simultaneously on first and second program channels, themapping information relating the first and second program channels to afirst physical channel; receiving, during the first period, usercommands to tune to the first or second program channels; andselectively tuning, based at least in part on the information, to thefirst physical channel regardless of whether the user commands the CPEto tune to the first or the second program channel.

In a third aspect of the invention, improved CPE for use in a cablenetwork is disclosed. In one embodiment, the CPE comprises: an interfaceconfigured to receive encoded content signals from the network;processing apparatus operatively coupled to the interface and adapted todecode the encoded signals received via the interface; and at least onecomputer program running on the CPE, the at least one program beingadapted to: receive a plurality of mapping data during a first periodwhen programming is scheduled substantially simultaneously on first andsecond program channels of the network, the mapping data relating thefirst and second program channels to a first physical channel; receive,during the first period, user commands to tune to the first or secondprogram channels; and selectively cause tuning of the interface, basedat least in part on the data, to the first physical channel regardlessof whether the user commands request tuning to the first or the secondprogram channel.

In a second embodiment, the CPE comprises: an interface configured toreceive content signals encoded according to a first service level, andalso encoded according to a second service level, from the network;processing apparatus operatively coupled to the interface and adapted todecode the encoded content signals received via the interface; and atleast one computer program running on the CPE, the at least one programbeing adapted to: utilize first data relating to a first period when thecontent signals encoded according to the first level are scheduledsubstantially simultaneously on first and second program channels of thenetwork, the first data relating the first and second program channelsto a first physical channel; and utilize second data relating to asecond period when the content signals encoded according to the firstlevel are scheduled on the first program channel substantiallysimultaneously with the content signals encoded according to the secondlevel scheduled on the second program channel, the second data relatingthe second program channel to a second physical channel.

In a fourth aspect of the invention, improved network apparatus for usein a cable network having a plurality of CPE is disclosed. In oneembodiment, the apparatus comprises: an interface configured to receivesignals from at least one of the CPE; processing apparatus operativelycoupled to the interface and adapted to process the signals received viathe interface; and at least one computer program, the at least oneprogram being adapted to: receive, via the interface and from the atleast one CPE, first signals requesting tuning to a first programchannel; assign at least one physical channel to the request; andtransmit second signals to the at least one CPE to permit the CPE totune to the at least one physical channel.

In a fifth aspect of the invention, a method of assigning physicalchannels within a cable network is disclosed. In one embodiment, themethod comprises: operating a first physical channel, the operatingcomprising broadcasting standard definition (SD) programming aver thephysical channel; receiving a request to view complementary highdefinition (HD) programming; and based at least in part on the request,assigning a second physical channel for broadcast of the HD programming.

In a sixth aspect of the invention, a method of operating a cablenetwork carrying content encoded according to first and second servicelevels (e.g., SD and HD, respectively) to a plurality of CPE operativelycoupled to the network is disclosed. In one embodiment, the methodcomprises: scheduling the content encoded at the first service levelonto first and second user channels of the network, the first and seconduser channels having first and second physical channels associatedtherewith, respectively; broadcasting the content encoded according tothe first service level on both the first and second physical channelssimultaneously, for a first period; broadcasting the content encodedaccording to the first service level on the first physical channel, andthe content encoded according to the second service level on the secondphysical channel, simultaneously, for a second period; selectivelytuning at least one of the CPE to only the first physical channel inresponse to a user of the at least one CPE attempting to tune to eitherof the first and second user channels during the first period; andselectively tuning the at least one CPE to the second physical channelduring the second period.

In a seventh aspect of the invention, a method of doing business withina cable network is disclosed. In one embodiment, the method comprises:offering at least one program at a first service level during a firstperiod on a plurality of program channels; and offering the at least oneprogram at a first service level on a first of the plurality of programchannels, and at a second service level on a second of the plurality ofprogram channels, during a second period; wherein access to the secondprogram channel during the second period is restricted to only a subsetof the users within the network. In one variant, the first and secondservice levels comprise SD and HD encoded content, respectively, andaccess to the second program channel is based on a given user'ssubscription level.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a functional block diagram illustrating an exemplary HFC cablenetwork configuration useful with the present invention.

FIG. 1 a is a functional block diagram illustrating one exemplary HFCcable network head-end configuration useful with the present invention.

FIG. 1 b is a functional block diagram illustrating one exemplary localservice node configuration useful with the present invention.

FIG. 2 is a logical flowchart illustrating a first embodiment of thebandwidth conservation methodology according to the present invention,wherein a single level of service is provided.

FIG. 3 is a logical flowchart illustrating a second embodiment of thebandwidth conservation methodology according to the present invention,wherein multiple service levels are provided.

FIG. 3 a is a logical flow diagram on an exemplary software processimplementing the methodologies of both FIGS. 2 and 3.

FIG. 4 is a functional block representation of a first exemplarysoftware architecture according to the present invention.

FIG. 4 a is a functional representation of a second exemplary softwarearchitecture according to the present invention, utilizing a distributedapplication.

FIG. 4 b is a functional representation of a third exemplary softwarearchitecture according to the present invention, utilizing a distributedapplication having client portions disposed at the CPE and local servicenode.

FIG. 5 is a functional block diagram illustrating an exemplary networkserver device according to the invention.

FIG. 6 is a functional block diagram illustrating an exemplary CPEdevice according to the invention.

DETAILED DESCRIPTION OF THE INVENTION

Reference is now made to the drawings wherein like numerals refer tolike parts throughout.

As used herein, the terms “user channel” and “program channel” are allgenerally synonymous with the concept of a perceived stream ofinformation. For example, a program/user channel might comprise “Channel3” which carries the content of a given network (e.g., NBC). This is tobe distinguished from a physical channel, which is used to physicallycarry and distribute the content, which may for example comprise one ormore QAMs within a given portion of the RF spectrum of a cable system.

As used herein, the term “QAM” refers to modulation schemes used forsending signals over cable networks. Such modulation scheme might useany constellation level (e.g. QAM-16, QAM-64, QAM-256 etc.) depending ondetails of a cable network. A QAM may also refer to a physical channelmodulated according to said schemes.

As used herein, the term “Service Group” refers to either a group ofservice users (e.g. subscribers) or the resources shared by them in theform of entire cable RF signal, only the RF channels used to receive theservice or otherwise treated as a single logical unit by the network forresource assignment.

As used herein, the terms “MSO” or “multiple systems operator” refer toa cable, satellite, or terrestrial network provider havinginfrastructure required to deliver services including programming anddata over those mediums.

As used herein, the terms “network” and “bearer network” refer generallyto any type of telecommunications or data network including, withoutlimitation, hybrid fiber coax (HFC) networks, satellite networks, telconetworks, and data networks (including MANs, WANs, LANs, WLANs,internets, and intranets). Such networks or portions thereof may utilizeany one or more different topologies (e.g., ring, bus, star, loop,etc.), transmission media (e.g., wired/RF cable, RF wireless, millimeterwave, optical, etc.) and/or communications or networking protocols(e.g., SONET, DOCSIS, IEEE Std. 802.3, ATM, X.25, Frame Relay, 3GPP,3GPP2, WAP, SIP, UDP, FTP, RTP/RTCP, H.323, etc.).

As used herein, the term “head-end” refers generally to a networkedsystem controlled by an operator (e.g., an MSO) that distributesprogramming to MSO clientele using client devices. Such programming mayinclude literally any information source/receiver including, inter alia,free-to-air TV channels, pay TV channels, interactive TV, and theInternet. DSTBs may literally take on any configuration, and can beretail devices meaning that consumers may or may not obtain their DSTBsfrom the MSO exclusively. Accordingly, it is anticipated that MSOnetworks may have client devices from multiple vendors, and these clientdevices will have widely varying hardware capabilities. Multipleregional head-ends may be in the same or different cities.

As used herein, the terms “client device” and “end user device” include,but are not limited to, personal computers (PCs) and minicomputers,whether desktop, laptop, or otherwise, set-top boxes such as theMotorola DCT2XXX/5XXX and Scientific Atlanta Explorer2XXX/3XXX/4XXX/8XXX series digital devices, personal digital assistants(PDAs) such as the Apple Newton®, “Palm®” family of devices, handheldcomputers, personal communicators such as the Motorola Accompli or V710,J2ME equipped devices, cellular telephones, wireless nodes, or literallyany other device capable of interchanging data with a network.

Similarly, the terms “Customer Premises Equipment (CPE)” and “hostdevice” refer to any type of electronic equipment located within acustomer's or user's premises and connected to a network. The term “hostdevice” refers generally to a terminal device that has access to digitaltelevision content via a satellite, cable, or terrestrial network. Thehost device functionality may be integrated into a digital television(DTV) set. The term “customer premises equipment” (CPE) includes suchelectronic equipment such as set-top boxes, televisions, Digital VideoRecorders (DVR), gateway storage devices (Furnace), and ITV PersonalComputers.

As used herein, the term “network agent” refers to any network entity(whether software, firmware, and/or hardware based) adapted to performone or more specific purposes. For example, a network agent may comprisea computer program running in server belonging to a network operator,which is in communication with one or more processes on a CPE or otherdevice.

As used herein, the term “application” refers generally to a unit ofexecutable software that implements a certain functionality or theme.The themes of applications vary broadly across any number of disciplinesand functions (such as on-demand content management, e-commercetransactions, brokerage transactions, home entertainment, calculatoretc.), and one application may have more than one theme. The unit ofexecutable software generally runs in a predetermined environment; forexample, the unit could comprise a downloadable Java Xlet™ that runswithin the JavaTV™ environment.

As used herein, the term “computer program” is meant to include anysequence or human or machine cognizable steps which perform a function.Such program may be rendered in virtually any programming language orenvironment including, for example, C/C++, Fortran, COBOL, PASCAL,assembly language, markup languages (e.g., HTML, SGML, XML, VoXML), andthe like, as well as object-oriented environments such as the CommonObject Request Broker Architecture (CORBA), Java™ (including J2ME, JavaBeans, etc.) and the like.

The term “component” in the context of software refers generally to aunit or portion of executable software that is based on a related set offunctionalities. For example, a component could be a single class inJava™ or C++. Similarly, the term “module” refers generally to a looselycoupled yet functionally related set of components.

As used herein, the term “server” refers to any computerized component,system or entity regardless of form which is adapted to provide data,files, applications, content, or other services to one or more otherdevices or entities on a computer network.

Overview

The present invention discloses methods and apparatus for conservingbandwidth on, e.g., a cable TV or other content-based network. Theinvention provides efficiencies to the network operator by takingadvantage of the fact that most programming (for most of the typicalbroadcast day and available channels) will be in an SD or otherlower-bandwidth format. For example, a given movie may be broadcast onuser or program Channel X in its analog or digital SD form, with an SDsimulcast on program Channel Y during parts of the day, and an HDsimulcast on program Channel Y during other parts of the day (e.g.,“prime time”). However, until the prime time or other designated HDbroadcast slot is reached, the HD simulcast on Channel Y will simplycomprise the same SD content available on Channel X. Thus by mapping theuser's Channel Y to the QAM channel for Channel X, the network operatorconserves “multicast” bandwidth associated with the SD content for asignificant fraction (often the majority) of the programming day.

The foregoing approach provides additional benefits and efficiencies,particularly when combined with a “switched digital” architecture; i.e.,one where a given service (level) is selectively provided to a localnode or service area when demanded. Specifically, in one exemplaryembodiment, the program stream is only instantiated for delivery to therelevant local node ad hoc; i.e., when a subscriber serviced by thatnode of the network attempts to tune to a particular program channel(e.g., Channel Y in the above example). This is somewhat akin to set-upof a conventional VOD session, yet without any real-time “trick mode”functionality. When the request for the program Channel Y is made,bandwidth for the broadcast session is assigned, and an OOB message orother communication is sent from the servicing entity (or head-end) tothe requesting CPE so that the CPE knows the PID/QAM channel to which itmust tune in order to receive and decode the Channel Y content. Whenother subscribers in the common service node/area desire to watchChannel Y, the servicing entity or head-end instructs their respectiveCPE to join the active broadcast of that program channel at theappointed tuner coordinates (e.g., PID/TSID/QAM).

In addition to SD and HD, other service levels (and types of services)can be used as the basis of the conservation management algorithmsdescribed herein. For example, VOD or IPTV (Internet Protocoltelevision) capability can be scheduled into a slot, such as during apromotional period, and the multicast bandwidth conserved until thescheduled slot begins, at which point any users tuning to the programchannel having the VOD or IPTV service scheduled will instantiate a newsession and physical channel assignment as previously described.

Improved network and CPE apparatus capable of implementing theaforementioned conservation methodologies are also described, as well asmechanisms to implement operational and/or business rules duringconservation management.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

Exemplary embodiments of the apparatus and methods of the presentinvention are now described in detail. While these exemplary embodimentsare described in the context of the aforementioned hybrid fiber coax(HFC) cable architecture having an multiple systems operator (MSO),digital networking capability, and plurality of client devices/CPE, thegeneral principles and advantages of the invention may be extended toother types of networks and architectures where bandwidth conservationis required or desirable, whether broadband, narrowband, wired orwireless, content or data, or otherwise. Hence, the followingdescription is merely exemplary in nature. For example, the inventionmay be practiced over a fiber-to-the-home (FTTH) or fiber-to-the-curb(FTTC) system or over future satellite or millimeter wave-based networkhaving two-way capabilities similar to today's digital cable HFCnetworks.

It will also be appreciated that while described generally in thecontext of a network providing service to a customer or consumer (i.e.,residential) end user domain, the present invention may be readilyadapted to other types of environments including, e.g.,commercial/enterprise, and government/military applications. Myriadother applications are possible.

It is also noted that while the following discussion is cast primarilyin terms of two service levels (i.e., SD and HD), the methods andapparatus disclosed herein can be extended to other numbers and types ofservice levels. For example, it is foreseeable that yet even higherlevels of definition may be employed in the future (e.g., “ultra-highdefinition” or UHD), thereby allowing intelligent bandwidth conservationbetween three service levels (SD, HD, and UHD). As another option,multiple levels or rates may be present with one of the aforementionedservice levels, such as where the SD level includes levels SD1, SD2, . .. SDn, and/or the HD level similarly includes HD1, HD2, . . . HDn, witheach of these sub-levels having different data rates and/or othercharacteristics. Alternatively, bandwidth conservation according to thepresent invention may be performed not based on definition level (datarate), but some other attribute such as for example the selectiveavailability of a type of service (e.g., OD, IPTV, or DVR/PVR). Variousalternate conservation schemes are described subsequently herein ingreater detail.

It is further noted that while described primarily in the context of 6MHz RF channels, the present invention is applicable to literally anyfrequency/bandwidth, such as for example 8 MHz channels. Furthermore, asreferenced above, the invention is in no way limited to traditionalcable system frequencies (i.e., below 1 GHz), and in fact may be usedwith systems that operate above 1 GHz band in center frequency orbandwidth, to include without limitation so-called ultra-widebandsystems.

FIG. 1 illustrates a typical content-based network configuration withwhich the bandwidth conservation methodology of the present inventionmay be used. The various components of the network 100 include (i) oneor more data and application origination points 102; (ii) one or moreapplication distribution servers 104; (iii) one or more VOD servers 105,and (iv) consumer premises equipment (CPE) 106. The distributionserver(s) 104, VOD servers 105 and CPE(s) 106 are connected via a bearer(e.g., HFC) network 101. A simple architecture comprising one of each ofthe aforementioned components 102, 104, 105, 106 is shown in FIG. 1 forsimplicity, although it will be recognized that comparable architectureswith multiple origination points, distribution servers, VOD servers,and/or CPE devices (as well as different network topologies) may beutilized consistent with the invention. For example, the head-endarchitecture of FIG. 1 a (described in greater detail below) may beused.

The data/application origination point 102 comprises any medium thatallows data and/or applications (such as a VOD-based or “Watch TV”application) to be transferred to a distribution server 104. This caninclude for example a third party data source, application vendorwebsite, CD-ROM, external network interface, mass storage device (e.g.,RAID system), etc. Such transference may be automatic, initiated uponthe occurrence of one or more specified events (such as the receipt of arequest packet or ACK), performed manually, or accomplished in anynumber of other modes readily recognized by those of ordinary skill.

The application distribution server 104 comprises a computer systemwhere such applications can enter the network system. Distributionservers are well known in the networking arts, and accordingly notdescribed further herein.

The VOD server 105 comprises a computer system where on-demand contentcan be received from one or more of the aforementioned data sources 102and enter the network system. These servers may generate the contentlocally, or alternatively act as a gateway or intermediary from adistant source.

The CPE 106 includes any equipment in the “customers' premises” (orother locations, whether local or remote to the distribution server 104)that can be accessed by a distribution server 104. Such CPEs 106comprise processors and associated computer memory adapted to store andrun the downloaded or resident application, as well as receive thestreamed in-band content. For example, “Watch TV” or similarapplications or their components (or updates thereto) of the typedescribed subsequently herein with reference to FIG. 6 can be downloadedto the CPE as required. For example, co-owned and co-pending U.S. patentapplication Ser. No. 10/655,655 filed Sep. 5, 2003 and entitled“Technique For Updating A Resident Application And Associated ParametersIn A User Terminal Through A Communications Network”, incorporatedherein by reference in its entirety, describes one exemplary techniqueand architecture for updating applications resident on network CPE.

Referring now to FIG. 1 a, one exemplary embodiment of a head-endarchitecture useful with the present invention is described. As shown inFIG. 1 a, the head-end architecture 150 comprises typical head-endcomponents and services including billing module 152, subscribermanagement system (SMS) and CPE configuration management module 154,cable-modem termination system (CMTS) and OOB system 156, as well asLAN(s) 158, 160 placing the various components in data communicationwith one another. It will be appreciated that while a bar or bus LANtopology is illustrated, any number of other arrangements as previouslyreferenced (e.g., ring, star, etc.) may be used consistent with theinvention. It will also be appreciated that the head-end configurationdepicted in FIG. 1 a is high-level, conceptual architecture and thateach MSO may have multiple head-ends deployed using customarchitectures.

The architecture 150 of FIG. 1 a further includes amultiplexer/encrypter/modulator (MEM) 162 coupled to the HFC network 101adapted to “condition” content for transmission over the network. Thedistribution servers 104 are coupled to the LAN 160, which providesaccess to the MEM 162 and network 101 via one or more file servers 170.The VOD servers 105 are coupled to the LAN 160 as well, although otherarchitectures may be employed (such as for example where the VOD serversare associated with a core switching device such as an 802.3z GigabitEthernet device). As previously described, information is carried acrossmultiple channels. Thus, the head-end must be adapted to acquire theinformation for the carried channels from various sources. Typically,the channels being delivered from the head-end 150 to the CPE 106(“downstream”) are multiplexed together in the head-end and sent toneighborhood hubs (FIG. 1 b) via a variety of interposed networkcomponents.

Content (e.g., audio, video, etc.) is provided in each downstream(in-band) channel associated with the relevant service group. Tocommunicate with the head-end, the CPE 106 may use the out-of-band (OOB)or DOCSIS channels and associated protocols. The OCAP 1.0 (andsubsequent) specification provides for exemplary networking protocolsboth downstream and upstream.

In another embodiment, the network infrastructure includes one or moreon-demand file or “carousel” functions. The present inventioncontemplates that not only will more traditional movie (e.g., MPEG)broadcast data be delivered though the bandwidth conservation mechanismsdescribed herein, but also data for interactive applications or othertypes of applications. For example, in a manner not unlike existingapproaches to ordering an on-demand (OD) movie, an application wouldrequest data, images, links, audio files, video files, and the like inan on-demand fashion. Hence, the OD downstream service can be considereda third and separate level of service (i.e., SD, HD, and OD), oralternatively can be considered as one or more subclasses within theexisting levels; i.e., where HD includes HD-OD. This concept isdescribed in greater detail below with respect to the switched digitalarchitecture embodiments. Myriad other organization schemes are alsopossible.

It will also be recognized that the multiple servers (broadcast, VOD, orotherwise) can be used, and disposed at two or more different locationsif desired, such as being part of different server “farms”. Thesemultiple servers can be used to feed one service group, or alternativelydifferent service groups. In a simple architecture, a single server isused to feed one or more service groups. In another variant, multipleservers located at the same location are used to feed one or moreservice groups. In yet another variant, multiple servers disposed atdifferent location are used to feed one or more service groups. Oneexemplary multi-server architecture particularly useful with the presentinvention is described in co-pending and co-owned United States PatentApplication Publication No. 20020059619 to Lebar published May 16, 2002and entitled “Hybrid central/distributed VOD system with tiered contentstructure” which is incorporated herein by reference in its entirety.

FIG. 1 b illustrates an exemplary “switched” network architecture usefulwith the present invention. Specifically, as shown in FIG. 1 b, thenetwork 101 of FIGS. 1 and 1 a comprises a fiber/coax arrangementwherein the output of the MEM 162 of FIG. 1 a is transferred to theoptical domain (such as via an optical transceiver 177 at the head-endor further downstream). The optical domain signals are then distributedto a fiber node 178, which further distributes the signals over adistribution network 180 to a plurality of local servicing nodes 182.This provides an effective 1:N expansion of the network at the localservice end, thereby leveraging the benefits provided by theconservation techniques described subsequently herein.

Many other permutations of the foregoing system components andcommunication methods may also be used consistent with the presentinvention, as will be recognized by those of ordinary skill in thefield.

Bandwidth Conservation Methods

Referring now to FIGS. 2-3, exemplary methods for conserving bandwidthin a content-based network are described in detail.

As previously referenced, the present invention advantageously providesefficiencies to the network operator by taking advantage of the factthat most programming (for most of the typical broadcast day andavailable channels) will be in an SD or other lower-bandwidth format.For example, a given video program may be scheduled on program Channel Xin its analog or digital SD form, with an HD simulcast on programChannel Y. Table 1 illustrates this relationship graphically:

TABLE 1 Program (User) Local Time Channel 6 pm 7 pm 8pm X SD SD SD Y(Simulcast of X) SD SD HDX and Y may also be related or constrained by some logical condition orfunctional relationship, such as e.g., where Y=X+N, N being an integer.

However, as is frequently the case, until the “prime time” or otherdesignated broadcast slot is reached, the HD simulcast on Channel Y maysimply comprise the same SD content available on Channel X. Thus bymapping the user's Channel Y to the QAM (physical channel) for userChannel X, the network operator conserves multicast bandwidth associatedwith the SD content for the majority of the day.

FIG. 2 graphically illustrates a generalized embodiment of themethodology described above. Specifically, the method 200 comprisesfirst scheduling content of a first service level (e.g., SD) on firstand second user channels per step 202. It is noted that step 202 merelyschedules the content, as opposed to actually distributing the contenton any physical channel or group of channels.

Next, the content of the first service level (e.g., SD) is distributedonto a first physical channel (e.g., one or more QAMs) per step 204.

The user of a given CPE thereafter tunes to the second channel, lookingfor the scheduled SD content per step 206. The tuning application (e.g.,Watch TV or the like) resident on the CPE 106 then accesses mappinginformation received from the head-end or servicing node, or requests it(step 208). If required, the servicing node responds with the mappinginformation (step 210), and the CPE subsequently employs the accessed orreceived mapping information to tune the CPE tuner to the first physicalchannel per step 212. Accordingly, the user believes that they havetuned to a second or discrete channel, when in fact they have tuned tothe same physical channel as if they had selected the first userchannel.

The mapping of the second user channel to the first physical channel canbe accomplished in any number of different ways, including mapping of aparticular program ID (PID) (and transport stream ID or TSID asrequired) to one or more QAM tuners within the CPE 106.

The foregoing method 200 advantageously conserves significant bandwidth,since the MSO or network operator need only utilize one physical channelto provide viewers with multiple “simulcast” program channels. This isparticularly important when multiple levels of service (e.g., SD and HD)are scheduled onto one of the two user channels, the presence of the HDprogramming requiring a second physical channel due to increasedbandwidth requirements. Specifically, during those periods when bothuser channels have SD programming scheduled (e.g., on a weekdayafternoon, or very early in the morning), the second physical channel isnot required, and hence the two user channels can be serviced by asingle physical channel (and the reduced bandwidth requirementsassociated therewith), the second user channel being mapped exclusivelyto the first user/physical channel during such periods.

Hence, in the exemplary embodiment of the invention, the channel mappingfor a given user Channel Y will depend on whether the content is asimulcast in SD format of the content shown on user Channel X (this maybe determined based on information as simple as the time of day and theuser Channel number), and will be implemented by the Watch TV or otherapplication using (i) information contained in a dedicated broadcast tothe CPE 106 from the head-end or servicing node 182 or its proxy (e.g.,additional information sent on the OOB carousel); (ii) contained in anelectronic program guide (EPG) received at the CPE 106; (ii) metadata orother information delivered in-band; and/or (iv) any combinationthereof.

During those periods where the HD service is scheduled onto the secondUI channel, there is a need to have two or more distinct physicalchannels due to, inter alia, the higher bandwidth requirements of the HDencoded content. The second physical channel(s) can be either onealready established and presently unutilized, or alternativelyestablished ad hoc, such as by simply allocating the HD content to oneor more QAMs at the time the HD programming is to begin, and instructingthe user's CPE to tune to a different QAM/set via the aforementioneddownstream OOB mapping communications. Regardless of how it isestablished, the different QAM/set is thereby available for other useswhen not carrying the HD content, such as e.g., carrying other SDprogramming or providing OD or DVR/PVR capacity.

It will also be recognized that the methodology 200 of FIG. 2 can bepracticed on a network where the second physical channel is notbroadcast, but rather established as a function of other events,including e.g., a user or CPE-initiated pull or request. Suchintelligent channel mapping provides additional benefits andefficiencies, particularly when combined with a “switched digital”paradigm. Co-owned and co-pending U.S. patent application Ser. No.09/956,688 filed Sep. 20, 2001 and entitled “Technique For EffectivelyProviding Program Material In A Cable Television System”, incorporatedherein by reference in its entirety, describes one exemplary switchedarchitecture useful with the present invention. The basic underlyingpremise of such switched architectures is that the differentiated (e.g.,HD) content is not transmitted or broadcast onto the network (or to thelocal node or entity servicing a given CPE) until there is a validrequest to view the HD content. Such request may comprise, for example,a given user's CPE tuning to the UI channel carrying the HD content, oranother signal from the CPE to the head-end or other servicing networkentity. In this fashion, the bandwidth of the network is conserved,since programming broadcasts or transmissions that no one is watchingare obviated.

The switched digital approach is further leveraged through the use of adistributed network architecture; i.e., the use of a plurality of localnodes or servicing entities such as that shown in FIG. 1 b. Consider thehypothetical case of where no local nodes are used, and hence all CPEare functionally coupled to a single node (e.g., the head-end). Underthe aforementioned switched digital approach, the first viewer desiringto view the HD content would cause an HD broadcast session to beinitiated, with the content being broadcast to the entire network. Thisis inefficient from a bandwidth conservation standpoint, since asignificant amount of the bandwidth of the entire network is used toservice as little as one viewer.

Conversely, in the limiting case where each separate premises had itsown dedicated local servicing node (and QAMs), each of these nodes couldswitch the HD broadcast on/off locally, thereby not affecting theoperation of the rest of the network. Additional bandwidth for theselected channel would only be required within the distribution pathfrom the head-end to that particular servicing node.

As can be appreciated, practical implementations of the switched digitalconcept will reside somewhere between these two extremes; i.e., with thenetwork having a plurality of local nodes, each node servicing aplurality of CPE/premises. It will also be appreciated that the term“local” as used herein need not refer exclusively to a geographic orspatial frame of reference, but may also comprise partitioning in alogical sense, such as where one node services a group of customers whoare logically proximate (e.g., based on service plan, demographics,viewing habits, OD consumption patterns, etc.).

FIG. 3 illustrates one exemplary embodiment of the method of bandwidthconservation using a switched approach. As in the method 200 describedabove, the method 300 of FIG. 3 comprises the MSO or operator schedulinga first level of service on a first user channel (step 302).Additionally, a second level of service (e.g., HD) is scheduled onto asecond user channel (step 304). Once a subscriber “tunes” to the userchannel carrying the HD content (step 306), and it is determined that(i) the HD content is available (step 308), and (ii) the present requestis the first request within the relevant network, e.g., within the CPEserviced by that particular local service node (step 310), an HD sessionis established (step 312), and the tuning (mapping) information is sentto the requesting subscriber's CPE 106 per step 314. Additionally, thetuning information can be sent to all (or a subset of the) other CPEwithin the original requesting subscriber's service node per step 314,so that these other “secondary” users can utilize the establishedswitched digital broadcast of the HD content.

Where it is determined that another CPE within the relevant “network”has already been assigned a physical channel for the selected programchannel per step 310, the channel tuning information for thealready-assigned physical channel is passed to the requesting CPE perstep 318. Note that this information may have already been passed to therequesting CPE when the earlier user established the channel, and canalso be used to obviate much of the method of FIG. 3 (i.e., thedetermination of the availability of the content per step 308, the firstrequest determination, and the establishment of the session and physicalchannel per step 312); see FIG. 3 a.

Unlike the channel mapping supporting the “broadcast” methodology ofFIG. 2, the foregoing channel mapping of the physical channel (e.g., QAMPID) to a user channel in the switched architecture (FIG. 3) isnecessarily dynamic. Specifically, depending on when the initial userselects a given program, and what service area/node they are associatedwith, the channel mapping will be varied as compared to that which mightoccur at another time/node. For example, the first demanded HD sessionin a given service node might be allocated QAM number A if initiated ata first point in time, while the same request might be allocated QAMnumber C if initiated at another time, due to the possibility that otherusers in the service group may be allocated a given set of QAMs for,e.g., a VOD session or the like. The first HD user in the service nodein effect anchors the channel allocation for subsequent HD users of thatsame user channel in the same service node, the allocation (mapping)being sent to each of the secondary users (or a subset thereof asdesired) after the first user's session is established as describedabove. This process is conducted within the framework of other channelallocations existing within the local service area at the time of thefirst HD session request; i.e., the HD session establishment process ofFIG. 3 will not allocate a QAM or set of QAMs that are already in usewithin that area.

FIG. 3 a illustrates one exemplary method 350 combining the methods ofFIGS. 2 and 3; i.e., to provide both bandwidth conservation of bandwidthduring SD/SD simulcast periods and “on-demand” like sessionestablishment during SD/HD simulcast periods.

The foregoing functionality of FIGS. 2 and 3 may be accomplished usingany number of different hardware/firmware/software configurations. Forexample, in one embodiment of the invention, the CPE is provided with aresident or downloaded application (e.g. “Watch TV” or similar) whichreceives channel mapping information from, e.g., the DNCS (DigitalNetwork Control System) at the head-end or other node of the network.The DNCS or other node provides the CPE with PID tuning information whenuser Channel Y is chosen, thereby mapping the user's Channel Y to userChannel X (and its associated physical channel) during those times whenonly a first level (e.g., SD) of programming is available on Channel Y.This mapping advantageously obviates the simulcasting of the SD contenton a second physical channel, thereby conserving bandwidth within theavailable QAMs.

Alternatively, it may be desirable to dispose the channel mappingfunction at a node more local to the user(s) as compared to thehead-end, since this approach acts to both (i) distribute the overheadassociated with receiving, processing, and providing the necessarychannel mapping information to a plurality of nodes, and (ii) place theresponding node closer to the requesting user, thereby reducingcommunication channel overhead back to the head-end. These “local”responding nodes may be integrated into the local service nodes 182 ofFIG. 1 b, and comprise e.g., a server with distributed softwareprocess(es), which may also be in communication with the head-end foradministrative functions as well as coordinating and updating thechannel allocation scheme and related functions (see FIG. 4, discussedsubsequently herein).

It will further be appreciated that one or more indirect sources may beused to provide the aforementioned mapping information, whether throughinterfacing directly with the CPE, or indirectly through another networkagent. For example, a proxy network entity (e.g., remote server) can beused to provide the mapping information via an IP connection (over thecable network or otherwise) to the CPE after the CPE transmits thechannel tuning request upstream to the local service node (or thehead-end). Alternatively, a wireless interface to the CPE (such as viaan 802.11 WLAN, 802.16 WiMax, or even 802.15 PAN interface) can be usedto deliver the mapping information. A satellite link may also be used toprovide the mapping information directly to a satellite receiverintegrated into or in communication with the CPE 106.

Furthermore, “pre-positioned” information may be used for mapping, suchas where one or more predetermined mapping tables or other informationconstructs are stored within the CPE 106 (or a connected device, such asan IEEE-1394 appliance), and recalled based on, e.g., informationtransmitted via the OOB or other link described above. For example, inone variant of the invention, the CPE is loaded with a plurality ofmapping tables during initial installation, or activation of a “premium”service plan or other feature/service. The individual tables areidentified by one or more coded parameters, and each contain a mappingscheme which can be used by the resident “Watch TV” or similarapplication on the CPE. Upon receipt of the coded parameters (such asvia the aforementioned OOB downstream channel), the CPE recalls thedesignated table, and applies the appropriate mapping contained therein.This approach obviates the need to download all of the mappinginformation, thereby reducing the overhead on the downstream channelused to transfer the mapping information (here, just the codedparameters). It will be appreciated, however, that in order to use thisapproach with the dynamic user channel/QAM allocation of the switcheddigital approach described above (FIG. 3), a scheme must be implementedwherein the channel allocations occurring at the local service node (orhead-end) are conducted according to a prescribed pattern or templatewhich corresponds to one of the tables accessible to the CPE.

Similarly, another variant of the invention uses an algorithm orpredetermined characteristics to spontaneously generate a mappingbetween channels. This algorithm is resident on both the CPE and theservicing entity (head-end, local node, etc.), and is coordinated suchthat the servicing entity passes a key or “seed” to the algorithm on theCPE. The seed is used by the algorithm to generate the required mappingaccording to the predetermined characteristics of the algorithm. As asimple example, consider the case where the mapping algorithm dictatesthat an established “simulcast” channel will always be mapped to theoriginal or base physical channel according to the formula of Eqn. (1):

Y=X+N  Eqn. (1)

Accordingly, the CPE programmed with this relationship need only knowthe value of X (or Y) to determine the mapping relationship. If thehead-end or other servicing network entity transmits the value of X or Yto the CPE, the CPE can apply the same algorithm to derive theappropriate channel mapping. This approach can be used for both theSD/SD mapping functions (FIG. 2) and the SD/HD functions (FIG. 3) asdesired. In the case of SD/SD mapping, the algorithm might know thatuser Channel X and simulcast user Channel Y are always separated by 100(e.g., X=7, Y=107, N=100), and hence when mapping user Channel Y to thephysical carrier of user Channel X, it need merely take the value of Y(107), subtract 100, and then apply the existing user-to-physicalchannel mapping of the result (i.e., 7).

Obviously, more sophisticated (and even dynamic) mapping algorithms maybe utilized consistent with the invention, including those that arenon-linear, or even deterministic based on other parameters such as timeof day, information resident on an electronic program guide (EPG)distributed to the CPE 106, operational conditions including equipmentfailure or maintenance, etc. For example, one approach would be to applya first algorithm such as that of Eqn. (1) above to a first range ofuser channels, a second algorithm to a second range, and so forth. Inone such scheme, base or original user Channels 1-10 could map tosimulcast user Channels 101-110, while base Channels 11-20 could map tosimulcast Channels 151-160. In a “maintenance mode”, Channels 11-20might map to simulcast Channels 211-220. Myriad other such schemes willbe appreciated by those of ordinary skill provided the presentdisclosure.

Using the foregoing approach, a user's tuning to the simulcast channel(say user Channel 151) would automatically be mapped by their CPE 106 tothe relevant base channel (i.e., user Channel 11) and its correspondingphysical channel seamlessly when no HD content was present.Alternatively, when HD content was available, the method of FIG. 3 wouldbe invoked by the CPE to both request and establish the “anchor” channelfor the HD session, and ultimately inform other CPE in the local node ofthe mapping information between the channel and the selected QAM(s).

It will be appreciated that other schemes may also be used for storingand retrieving the mapping information, such as providing theinformation encoded or contained within an in-band transport stream (TS)that is already being delivered to the premises requesting the newchannel. Hence, where the customer is viewing user Channel A, and wishesto switch to Channel Y (the otherwise simulcast version of Channel X),the CPE signals the head-end (such as via existing upstream OOBsignaling mechanisms) that a change to a “mapped” channel is requested,and the head-end or other node responds with mapping information, suchas a mapping table or coded parameters as described above) which areincluded within the TS carrying Channel A. The mapping information orparameters are retrieved from the decoded TS, and immediately applied bythe resident application and CPE tuner stages to tune the CPE to thephysical channel(s) associated with user Channel X (even though userChannel Y was selected). In the event that the user is switching to auser channel scheduled to be carrying HD, the methodology of FIG. 3 isthen invoked, with the tuning of the CPE being conducted according toPID/TSID/QAM or other similar information contained within the encodedtransport stream carrying user Channel A.

It will further be recognized that the mapping of channels may occur ona non-exclusive basis, such as where content is broadcast or otherwiseprovided over a base channel and simulcast on a plurality of otherchannels. In the context of the foregoing example, such a mapping mightcomprise base user Channel X being mapped to user Channels Y₁ and Y₂.This might be the case where a given SD program is distributed on afirst channel and simulcast on more than one other channel. Thus, theuser's CPE according to the present invention would map selection ofeither Channel Y₁ or Y₂ to Channel X. This situation would provide yetfurther leverage to the MSO or network operator, since two simulcastchannels could be “collapsed” in favor of the base channel of the sameservice level.

In one exemplary embodiment of the invention, the times and servicelevel of various programming is made available to the “Watch TV” orother resident application of the CPE via programming metadata of thetype well known in the art, e.g., similar to that made available topopulate the CPE's electronic programming guide (EPG). Generallyspeaking, “metadata” comprises extra data not typically found in (or atleast not visible to the users of) the network. This metadata may bevalidated against relevant specifications if desired, such as thoseprovided by CableLabs. The metadata might specify the date, GMT or otherstart time reference, duration, service level (e.g., SD or HD), andPID/TSID/QAM channel(s), and can be rendered in human-readable form ifdesired. It will be recognized that additional and/or different metadatacontent may be used consistent with the invention. The metadatainformation can be packaged in a prescribed format such as a markuplanguage (e.g., XML). The metadata (files) may also be encrypted;encryption algorithm information of the type well known in the art mayalso be included.

Metadata may also be used for conveying and formatting upstream data andrequests, such as that sent by the Watch TV or other CPE applicationupstream to the head-end servers or servicing network entities. Thisinformation might include, e.g., CPE or customer identifyinginformation, CPE profile data, maintenance and error-related data, etc.

Similarly, data on the user's channel switching patterns can becollected and sent upstream; e.g., where the CPE applications logs theuser's channel changing patterns during simulcast periods in order tofeed a head-end database or algorithm which can attempt to optimize oneor more aspects of its own operation based on the data. Suchoptimization might comprise, e.g., delaying the tearing down of existingprogram streams, or setup of new streams at a particular local node,where the user's anecdotal upstream metadata indicates that they are arapid “channel hopper”.

The process of establishing or tearing down user-initiated sessionsaccording to the invention can be made as prompt or latent as desired.For example, in one embodiment, the program table or schedule for agiven user channel is evaluated by an algorithm running on the CPE 106(e.g., as part of the modified Watch TV application described elsewhereherein, or as a stand-alone process) to identify substantiallycontiguous HD programs that may be separated only by short durationevents such as advertisements, promotions, introductions, etc. In thisfashion, rapid collapse of the HD session upon the completion of a firstHD program (and subsequent switching to a mapped SD simulcast) when noother local users are viewing can be selectively avoided if desired,possibly based on the expectation that the viewer will continue watchingthe second HD program. Alternatively, where maximal bandwidthconservation is desired, the sessions can be made to collapseimmediately, thereby freeing as much bandwidth as possible at all times.Such immediate collapse might also be driven in part by anecdotal orstatistical data indicating that, e.g., this user or users in general,respectively, tend not to watch two HD programs in sequence, tend not towatch two programs of the given genre in sequence, and so forth. Myriaddifferent criteria for determining whether or not to rapidly tear down agiven session will be recognized by those of ordinary skill given thepresent disclosure.

The bandwidth conservation mechanisms described herein may also be usedwith other bandwidth allocation and optimization mechanisms. Forexample, the methods and apparatus described in co-owned and co-pendingU.S. patent application Ser. No. 10/881,979 filed Jun. 29, 2004 andentitled “METHOD AND APPARATUS FOR NETWORK BANDWIDTH ALLOCATION”,incorporated herein by reference in its entirety, may be used to provideenhanced allocation of bandwidth between SD and HD sessions acrossmultiple physical channels (QAMs) or even logical channels within thenetwork. The allocation mechanisms and schemes can be forwardeddownstream, for example, to the servicing nodes 182 and the CPE 106 viaan OOB channel or other means, such that each device knows thescheduling of SD and HD programs on the various different sets of QAMs.

Also, the physical channels provided by the bearer network can becomprised of a plurality of constituent channels, as is described inco-owned and co-pending U.S. patent application Ser. No. 11/013,671filed Dec. 15, 2004 and entitled “Method And Apparatus For WidebandDistribution Of Content”, incorporated herein by reference in itsentirety. For example, the content of a given TS can be multiplexedacross a plurality of physical carriers using a wideband approach. Themultiplexed signal is reassembled at the CPE 106 using a wideband tuner(or a plurality of related tuners) and information from the head-end asto the multiplexing scheme and channels used. Hence, for the purposes ofthe present invention, the aggregation of multiplexed channels acts likea single QAM.

Software Architecture

Referring now to FIG. 4, one exemplary embodiment of the softwarearchitecture of the present invention is described. While the followingdiscussion is cast in terms of one or more Conservation BandwidthManager (CBM) entities resident at the servicing node and/or distributedover the various components of the network, it will be appreciated thatother architectures may be used.

As shown in FIG. 4, the basic CBM architecture 400 of the inventioncomprises a CBM entity 402 running on the servicing node 404 (e.g., thehead-end 150, or alternatively the local service node 182) which is inprocess communication with the exemplary Watch TV (or similar)applications 406 running on the CPE 106. The CBM entity 402 operates to,inter alfa, (i) receive session requests associated with HD userchannels from the CPE 106 during HD simulcast periods; (ii) determinewhether other sessions for that same user channel are established; (iii)verify that the requested HD content is in fact available for broadcast;(iv) assign bandwidth (QAMs) to the incoming session requests when therequested content is available and no other sessions are establishedwith the local service area; and (v) transmit the physical channelallocation (tuning) information to the CPE within the relevant servicearea when a channel has been established, thereby allowing the CPE 106to map the selected user channel to the assigned physical channel.

Session requests are received by the CBM 402 from the CPE via upstreamOOB channels (reverse data channels) or other pathways, and processedwithin the CBM to extract the required information contained thereinincluding, e.g., the requested channel or program ID. Other informationmay also be included within the request and extracted at the CBM 402,such as local service node ID, CPE or user ID, a transmission or localtimestamp, coding, CRC or encryption data, etc. Any number of differentprotocols can be used for this purpose, such as for example thosespecified in Part 6 of “MPEG-2: Digital Storage Media-Command AndControl” (referred to as DSM-CC) defined under the ISO/IEC 13818-6International Standard, a Trivial File Transfer Protocol (TFTP), RealTime Protocol (RTP/RTCP), TCP/UDP, or Session initiation Protocol (SIP).

In one embodiment, the request process is user-agnostic; i.e., the CBM402 need not identify which CPE in particular issued the sessionrequest, but rather need only know which local node 182 the requestingCPE is serviced by. This is possible since the tuning/mappinginformation ultimately generated by the CBM 402 after channel allocationand session initiation can be broadcast to all CPE 106 within therelevant local node. There is, under this paradigm, no intrinsic benefitto identifying which CPE initiated the local session; all that the CBM402 need know at any given point in time is that an (HD) session exists,or it does not.

In another variant, the CBM 402 is given additional “intelligence” tospecifically identify the requesting CPE 106. This functionality can beaccomplished by the CBM extracting the CPE or user ID information fromthe request message as previously described. This approach may be usefulwhere it is desirable to validate or authenticate a request, or arequest from a particular user as compared to another (such as whereselective or premium service plans are in effect).

Determination of the existence of other sessions for the same userchannel the simulcast HD channel) is performed by the CBM 402 by, e.g.,evaluating a local or global counter of session requests within aprescribed period of time. Where no session requests have been received(counter=0), the algorithm for establishing a new session (andallocating a new QAM) is entered. Where the counter ≧1, the CBM 402enters an algorithm to (i) obtain the relevant tuning information forthat session, and (ii) transmit this information to all or a subset ofthe CPE within the local service area.

As noted above, the CBM 402 may also optionally determine whether therequested (HD) content is in fact available for broadcast. This can beaccomplished by, e.g., signaling another process within the head-end 150or local service node 182, or alternatively periodically evaluatingservice or status messages issued by a content source entity within thehead-end. The former approach advantageously reduces network overhead,since status messages/signals are only issued when required, as opposedto periodically (whether they are needed or not).

In terms of transferring the tuning information to the CPE (requestingand otherwise), one embodiment of the invention simply broadcasts thetuning information for the assigned physical channel to each of the CPEwithin the relevant portion of the network (e.g., local service area)when it is obtained. Alternatively, the tuning information can be issuedon a demand/request basis only, such as where the Watch TV or similarapplication within the CPE tuning to the already assigned and mappeduser channel issues a request for tuning information. This request caneven take on substantially identical form to the request issued forsession establishment (discussed previously) if desired. The CBM 402receives the request, checks the counter or other indicia to determinethat a session has already been established, and then issues the tuninginformation.

FIG. 4 a illustrates an alternate software architecture 440 according tothe invention, wherein the CBM 442 comprises a distributed application(DA) of the type well known in the programming arts. For example, theapparatus and methods described in U.S. Pat. No. 6,687,735 to Logston,et al. issued Feb. 3, 2004 and entitled “Method and apparatus forbalancing distributed applications”, incorporated herein by reference inits entirety, may be used consistent with the present invention. Theserver portion 444 of the CBM 440 at the servicing node communicateswith the client portion(s) 446 at each CPE 106 via in-band or OOBphysical channels, thereby forming logical channels between theservicing node process 444 and the CPE portion 446. The client portion446 also communicates with the Watch TV 406 or other application withinthe CPE 106.

FIG. 4 b illustrates another alternate software architecture 460according to the invention, wherein the CBM 462 comprises a distributedapplication (DA) which has client portions 466, 468 located both on thelocal service node 182 (e.g., on the server device of FIG. 5) and theCPE 106. The server portion 464 of the CBM 460 at the head-end 150communicates with the CPE client portions 468 indirectly via the servicenode client portion 466. As in the embodiment of FIG. 4 a, the CPEclient portions 468 also communicate with their respective Watch TV 406or other application within the CPE 106. The Watch TV application 406may also be configured to communicate directly with the service nodeclient portion 466 if desired. Furthermore, as described in greaterdetail below, the service node client portion 466 may be incommunication with those of other nodes in order to coordinate bandwidthconservation efforts including, e.g., the allocation of channels to HDsession requests.

Referring now to FIG. 5, a first embodiment of the improved networkserver device with bandwidth conservation capability according to thepresent invention is described. It will be appreciated that whiledescribed in the context of a device disposed at the head end or localservice node 182 of FIG. 1 b, the device may be adapted for use at otherlocations within the network.

Server Device

As shown in FIG. 5, the device 501 generally comprises anOpenCable-compliant network server module including a digitalprocessor(s) 504, RAM 505, mass storage device 506, and a plurality ofinterfaces 507 for connection with other network apparatus such as LANs,the local service node hardware, IP routers and other packet networkdevices, network management and provisioning systems, local PCs, etc.Other components which may be utilized within the server device 501(depending on where it is employed and how it is physically implemented)include RF tuner stages, modulators/demodulators, encryption/decryption,amplifiers, board level electronic components, as well as mediaprocessors and other specialized SoC or ASIC devices. Support forvarious processing layers and protocols (e.g., 802.3, DOCSIS MAC, OOBchannels, DHCP, SNMP, H.323/RTP/RTCP, VoIP, SIP, etc.) may also beprovided as required.

The server device 501 of FIG. 5 may take any number of physical forms,comprising for example one of a plurality of discrete modules or cardswithin a head-end component or local service node device of the typewell known in the art. The server may also comprise firmware, eitheralone or in combination with other hardware/software components such asthose previously described. Alternatively, the server module 501 may bea stand-alone device disposed at the head-end, local node or otherlocation. Numerous other configurations may be used. The server device501 may also be integrated with other types of components (such assatellite transceivers, encoders/decoders, etc.) and form factors ifdesired.

It can also be appreciated that the methods of the present invention maybe practiced using any configuration or combination of hardware,firmware, or software, and may be disposed within one or any number ofdifferent physical or logical entities. For example, the CBMfunctionality described above may take the form of one or more computerprograms running on a single device disposed within the network (such asthe server module 501), such as at a head-end, node, or hub. As yetanother example, portions of the functionality may be rendered as adedicated or application specific IC having code running thereon. Myriaddifferent configurations for practicing the server device of theinvention will be recognized by those of ordinary skill in the networkarts provided the present disclosure.

Exemplary CPE

FIG. 6 illustrates a first embodiment of the improved CPE 106 accordingto the present invention. As shown in the simplified diagram of FIG. 6,the device 106 generally comprises and OpenCable-compliant embeddedsystem having an RF front end 602 (including tuner anddemodulator/decryptors) for interface with the HFC network 101 of FIGS.1-1 b, digital processor(s) 604, storage device 606, and a plurality ofinterfaces 608 (e.g., video/audio interfaces, IEEE-1394 “Firewire”, USB,serial/parallel ports, etc.) for interface with other end-user apparatussuch as televisions, personal electronics, computers, WiFi or othernetwork hubs/routers, etc. Other components which may be utilized withinthe device (deleted from FIG. 6 for simplicity) various processinglayers (e.g., DOCSIS MAC or DAVIC OOB channel, MPEG, etc.) as well asmedia processors and other specialized SoC or ASIC devices. The CPE 106may also comprise an integrated HD decoder, thereby relieving anyconnected monitors or other devices from the requirement of having sucha decoder. These additional components and functionality are well knownto those of ordinary skill in the cable and embedded system fields, andaccordingly not described further herein.

The CPE 106 of FIG. 6 is also provided with an OCAP 1.0-compliantapplication and Java-based middleware which, inter alia, manages theoperation of the device and applications running thereon. It will berecognized by those of ordinary skill that myriad different device andsoftware architectures may be used consistent with the tuning functionsof the present invention, the device of FIG. 6 being merely exemplary.For example, different middlewares (e.g., MHP, ARIB, or ACAP) may beused in place of the OCAP middleware of the illustrated embodiment.

The exemplary CPE 106 further comprises a conventional “Watch TV”application 406 or the like, which services those program or userchannels available over the network. The Watch TV application, residingin memory, provides such functions as channel navigation control,channel selection in response to a channel change event, etc. In theillustrated embodiment, the Watch TV application further comprises allnecessary functionality need to support both the channel mapping andsession request/setup features previously described with respect toFIGS. 2 and 3.

Specifically, regarding channel mapping, the application is configuredto map the user's (program) channels to corresponding physical channelsthrough use of program IDs, transport stream IDs, or other similarinformation as is well known in the art. Several salient distinctionsexist over the prior art, however, including that the application of thepresent invention is further adapted to (i) map 2 or more programchannels to the same physical channel(s); and (ii) utilize schedule orother data to selectively implement the mapping.

The utilization of the schedule or other data can be accomplished in anynumber of different ways. For example, in one variant, the Watch TV orother application 406 is adapted to identify data (e.g., metadata)contained within one or more communications from an external network orthird party entity. As previously described, such data may betransmitted via a downstream OOB channel, in-band, or via an alternateinterface such as an IP channel or wireless interface. This data may becontained in a dedicated communication (e.g., an OOB “mapping” messageformat or protocol), or included with another scheduled or unscheduledcommunication from the network (such as an EPG download, applicationdownload, CPE profile query, etc.). The data may also be resident on theCPE before use, such as where mapping tables are stored in memory ormass storage and subsequently accessed as previously described.

The CPE application of the present invention is also optionallyconfigured to generate requests or signals to the servicing networkentity (e.g., local node 182 in FIG. 1 b, or the head-end 150) that aretransmitted upstream to initiate the allocation of one or more physicalchannels and the spawning of a new session for the CPE. As previouslydiscussed, this request may comprise, e.g., a simple message addressedto the relevant software process within the servicing entity (or itsproxy formatted according to any number of well known protocols, oralternatively some other type of communication. The application is alsoconfigured to receive communications from the servicing node, head-end,third party network entity, etc. containing the PID/QAM/TSID tuninginformation which enables the CPE 106 to tune to the newly assignedphysical channel (and map the program channel thereto).

However, as noted above, this mapping is potentially dynamic (if outsideany programmed tear-down latency period previously discussed), since thelogic utilized by the servicing entity to assign the physical channelfirst checks to see if other physical channels have already beenassigned within that local service node (see discussions of FIGS. 3 and4 above) when servicing the HD session request. If so, the servicingentity merely passes the existing channel tuning information to therequesting CPE (as opposed to allocating a new channel). Thus, if agiven user tunes away from the HD-carrying program channel for whichthey were the first user within their service node, and thensubsequently tunes back, they may or may not be passed the same tuninginformation (e.g., since other CPE may now be tuned to the samechannel). If other CPE is using the same HD user channel, then there-joining CPE will be passed the same information. If no other CPE isusing the HD user channel, and the session is torn down in theintervening period between the tune-away and the tune-back, a newphysical channel (e.g., QAM or QAM set) will be allocated by theservicing entity, which may or may not be the same one(s) as before.

Stagger-Cast Variants

It will be recognized that the apparatus and methods of the presentinvention can also be used to afford noted benefits such as increased HDdensity. This could, for example, be used to provide increased near-VOD(NVOD) capability. Specifically, in one embodiment based on the switcheddigital architecture previously described, programming is “stagger-cast”such that time-shifted copies of a given high vide quality (e.g., HD)program are transmitted over one or more QAMs allocated to the HDsession request issued by a given CPE. Stagger-cast is a process whereinidentical copies of the same program, with their start times staggeredby some duration, are multiplexed with each other to form a transportstream. When a viewer tunes to the transport stream, the viewer canstart watching the program from the beginning as soon as the start of anext staggered copy of the program is received. This results in aVOD-like functionality without having to wait for a long period of time(e.g., until the next scheduled iteration of the complete movie, such asthe next 2-hour slot). For example, twenty-four copies of a movie of 120minutes duration can be staggered to start 5 minutes apart in a singlecable QAM channel, with each copy being assigned approximately 1.2 Mbpsbandwidth. When the viewer tunes into such a multiplex, he is never morethan 5 minutes away from starting point of a copy of the program.

As noted above, each time-shifted version of the program comprises adifferent broadcast. Thus, the MSO can provide the user with a near-VODcapability, with the level of latency (i.e., how “near” the NVOD reallyis to true VOD, such as the 5 min. referenced in the above example)being determined by the metrics of the time delay and multiplexingprocess.

Hence, in one variant, the NVOD or stagger-cast service provided to auser within a given local service area or node can be instigated basedon an HD session request from that user, as opposed to being constantlybroadcast into that node. When the first user's session is established,and one or more QAMs allocated as previously described herein, the TSbroadcast onto the allocated QAM(s) can comprise a plurality ofstagger-cast copies of the requested HD program. As other users withinthe same service area/node tune into the scheduled HD broadcastthereafter, they can be given the option (as can the session-initiatingCPE) of joining at the in-progress (i.e., non-time shifted) portion ofthe TS multiplex, or alternatively a time-shifted portion. Hence,late-arrivers can still catch the beginning of the program, and any ofthe users on the service node can be given NVOD capability.

Furthermore, where no other HD programming is scheduled into the slotfollowing the aforementioned stagger-cast HD program, the staggeredcopies of the HD program can literally run over the top of the followingSD broadcast on the same program channel, because the other aspects ofthe present invention (i.e., mapping of the simulcast SD program channelto the “base” SD program channel during SD/SD periods) allows the CPE106 to map the simulcast program channel back to the base channel if theuser desires to watch the follow-on SD programming. Note that thisinformation (i.e., the schedule information indicating that an SD/SDperiod is beginning) is already present within the CPE, such as from theEPG, as previously described with respect to FIG. 2 herein.

Alternatively, if the viewer wants to continue to watch the HDstagger-cast (assuming they are watching a copy which runs into thefollow-on SD slot), they can just stay tuned to the physical channelassociated with the established HD session. Different mechanisms areenvisioned for giving the user various levels of control over thisprocess if desired, including for example (i) offering the user anon-screen and/or audible prompt at the point where the HD stagger-castprogram begins to run into the subsequent SD slot, and allowing the userto choose which they desire to watch; (ii) keeping the user locked ontothe current (HD) physical channel unless they tune away to the SD “base”program channel or other program channel; or (iii) automatically tuningthe user away from the HD simulcast channel to the SD base programchannel, and requiring the user to tune back to the simulcast (HD)program channel (and hence its associated physical channel carrying thestagger-cast HD TS) and rejoin their stagger-cast copy, or a later oneif available.

Note that if the latent HD viewer is the sole remaining user on the HDsession, and they tune away from the session for a period of timeallowing the HD session within their service node to collapse, asubsequent request to rejoin the “latent” HD session can optionally behonored simply be re-allocating the stagger-cast TS stream to a new QAM(or even the same one), and advise the requesting user accordingly aspreviously described with respect to FIG. 3. Hence, the user (and anyother users who want to join the latent HD session late) is notpenalized for switching, or being switched, away. In one embodiment,when the last stagger-cast copy within the TS is complete, then theoperation of the user's CPE 106 simply reverts to its normal behavior(i.e., maps to an existing base SD physical channel when the simulcastprogram channel is selected).

At completion of the latent HD program, the CPE can be programmed toimmediately map (tune) to the physical channel associated with the baseSD program channel if desired, thereby making the transition between theend of the HD stagger-cast program copy and the “in-progress” SDbroadcast program largely seamless. This seamless transition isadvantageously available regardless of which stagger-cast copy the HDviewer is watching; the CPE 106 simply maps to the SD base programchannel when the HD program is completed (as can be determined by anynumber of mechanisms, such as in-band or OOB signaling, expiration of alocal clock, etc.).

Alternative to allowing the stagger-cast copies to run into thefollowing (SD) slot on the simulcast program channel is scheduling theslots of both the SD version and the simulcast HD version as NVODevents, each with a common overall duration which exceeds the program'sactual length by some amount. The physical channel providing theotherwise broadcast SD content can also be stagger-cast if desired(e.g., utilize a multiplexed TS), with even finer granularity, i.e.,less user latency, than the HD simulcast due to the increased bandwidthrequirements of HD over SD. This “simulcast SD NVOD” is at the expenseof system bandwidth however, since the staggered copies of the SDbroadcast consume capacity which could otherwise be used for othercontent.

It will be appreciated that under any paradigm, there is a trade-offbetween the aforementioned latency versus and the number of copies ofthe same program that are multiplexed together. For example, the aboveexemplary stagger-cast stream could also be constructed using 12 copiesof the program, staggered to start 10 minutes apart. Therefore, if aservice provider wants to offer to the viewers a service that reducesthe wait or latency of a given point in the program being againaccessible, more copies of the programs will have to be multiplexedtogether.

If a stagger-cast technique is to be applied to high quality programs(such as HD programs) at the typical 12-18 Mbps compression rate, onlyabout 3 copies can be stagger-cast together. However, if desired, thisrate can be significantly increased by implementing the widebandmultiplex apparatus and methods described in application Ser. No.11/013,671 filed Dec. 15, 2004 and entitled “Method And Apparatus ForWideband Distribution Of Content” previously incorporated herein.Specifically, by using the wideband multiplex with multiple (e.g., 8, 4,or 2) QAMs, additional bandwidth is available to include more copies,thereby reducing the wait time or latency experienced by the viewer. Asan example, in a wideband multiplex consisting of four QAM channels, 12copies of an HD program of 120 minutes duration each can bestagger-cast, assuming 12 Mbps each, with the resultant wait time beingless than 10 minutes.

Therefore, the use of a wideband multiplex offers a system operator theability to provide high quality (e.g., HD) stagger-cast near-VODservices with minimal user wait time. However, even with no widebandmultiplex, the operator can provide HD stagger-cast (and hence NVOD),just with a longer latency than would be available using the widebandapproach.

Operations/Business Rules Engine

In another aspect of the invention, the aforementioned CBM (e.g.,rendered as one or more computer programs) includes a so-called “rules”engine. This engine comprises, in an exemplary embodiment, a series ofsoftware routines running on the server device 501 or other associatedhardware/firmware environment adapted to control the operation of theCBM algorithms previously described. These rules may also be fullyintegrated within the CBM 402 itself, and controlled via e.g., a GUI ona PC connected to the server 501. In effect, the rules engine comprisesa supervisory entity which monitors and selectively controls, via theCBM 402, (i) the mapping of program or user channels to physicalchannels for the CPE 106 within the designated service area, (ii) theestablishment and tear-down of physical channels and sessions inresponse to requests for HD or other such content, and (iii) theprovision of tuning information to the CPE. The rules engine dynamically(or manually) controls the operation of the CBM 402 to implement aprescribed set of rules; hence, the CBM 402 can be thought of as a“toolbox” by which the rules engine implements its higher-levelsupervisory and analytic functions. These rules may be, e.g.,operational or business-oriented in nature, and may also be appliedselectively in terms of time of day, duration, specific local areas, oreven at the individual user level.

For example, one rule implemented by engine may comprise only mapping anSD program scheduled on a simulcast user channel to a common physicalchannel with the “base” SD user channel (as described with respect toFIG. 2 herein) when a certain operational parameter is reached; e.g., acertain level of bandwidth consumption within the network. Another rulemight comprise instigating such mapping when there is a QAM or otherhardware failure on the network, thereby conserving the remainingbandwidth for user content delivery.

Regarding establishment of the HD session, one rule might impose amoratorium on establishing or allocating new physical channels/QAMs toHD session requests until a certain minimum threshold of availablebandwidth is present, thereby avoiding contention for bandwidthresources with “premium” services such as VOD or the like. Specifically,as the available bandwidth on the network (or within a given local node)runs low, it may be desirable to impose a rule that prevents allocationof the few remaining QAMs to HD sessions, since those users already haveaccess to the corresponding “simulcast” SD programming via an existingQAM, and will only be deprived of the enhancement of HD over SD. Rather,it may perhaps be preferable to give first access to the remainingbandwidth assets to those customers with the highest subscription plans,longest subscription tenure, or the highest profit margin per unitbandwidth.

Should suitable additional bandwidth become available during the “HDbroadcast”, then the users submitting requests for the HD content couldbe selectively switched over to the newly established QAM(s) supportingthe HD sessions.

It will also be appreciated that advertising or other comparableservices (such as “TV-commerce”) can be considered a “service level”which can act as the basis for channel assignment and conservationdecisions. Specifically, HD sessions or other bandwidth-consuming eventscan be allocated to those users which will make best use of thebandwidth in terms of monetary return, profit, or some other businessperformance metric. However, the advertising/service itself can be usedas a basis or parameter on which bandwidth conservation decisions aremade, such as where it is desired to support a minimum level ofadvertising or TV-commerce service first before then allocatingbandwidth to simulcast HD sessions as previously described with respectto FIG. 3. Hence, an MSO or other entity may actually set aside or delayHD session requests in favor of advertising or commerce-relatedbandwidth. Similarly, the MSO may desire to have a certain minimum levelor quota of gaming or other content. Many other approaches andcombinations are envisaged consistent with the invention.

The establishment of the HD or similar session in response to the user'stuning request (e.g., as shown in FIG. 3) might also be treated as apremium or even “pay per” event if desired. For example, during periodswhen the SD content is scheduled for simulcast (and hence the simulcastprogram channel is mapped to the base program channel (and itsassociated physical channel), the user would be given unlimited access.However, during periods when the HD simulcast is scheduled, the user'saccess might be restricted or authenticated, such as by applying a rulethat says that only customers with a certain subscription level (asdetermined by data resident either at the head-end, servicing node, oron the CPE itself) will be provided access. This access can also be madeconditional, such as where the aforementioned rule is only applied whentotal available bandwidth at the node (or even network-wide) is below aprescribed level. If the user's access is restricted, the tuning eventcan be made to appear seamless (i.e., they just remain tuned to thephysical channel carrying the SD content), or alternatively the user canbe given a prompt to take some further action, a notice that the HDcontent is not available to them, etc.

In another alternate embodiment where wideband tuners are utilizedwithin the network infrastructure and CPE (see, e.g., U.S. patentapplication Ser. No. 11/013,671 entitled “Method And Apparatus ForWideband Distribution Of Content”, previously incorporated herein),other operational/business rules may be applied. For example, a QAMmultiplex set for a given wideband CPE might comprise 8 different QAMsunder normal (i.e., non-constrained) bandwidth conditions. However, whenbandwidth conservation is imposed, all or a subset of the wideband setscan be collapsed to a lesser number of QAMs, such as 4 or even 2. Thisreduction of QAMS in each set has the effect of degrading the pool sizeand hence statistics associated with the wideband statisticalmultiplexing process; however, this degradation may be more than offsetby the gains in available QAMs for, e.g., premium services or the like.Note that under certain circumstances, additional bandwidth may actuallybe gained by increasing the number of QAMs within a wideband multiplex.Hence, the present invention contemplates the manipulation of QAMmultiplex set size in either direction as may be dictated by operationalor other considerations.

The aforementioned rules engines of the exemplary CBM may be implementedin a local or global (i.e., network-wide) fashion. For example, in onevariant, the CBM and associated rules engine operate at the localservice node level, in effect treating the local node as the entirenetwork for purposes of bandwidth conservation. In another variant, theCBM/rules engine is applied across multiple local service nodes. In yetanother variant, the CBM/rules engine is applied globally across theentire network.

Note that when operating at the local service node level, the CBM/rulesengine of the present invention may communicate with other processes(e.g., other CBM/rules engines for other local service areas) in orderto optimize the operation of one or both. As a simple example, considermultiple local service areas distributed over multiple time zones; wherecertain operational conditions exist in the first time zone (e.g., veryhigh demand for particular services such as HD programming associatedwith an event which is also staggered across the zones). Thisoperational profile data can be transmitted to the CBM/rules engine of aservice area in a later time zone to compensate for the increased RDdemand.

As another example, local service nodes which have the option ofswitching between two parent or source nodes might base such switchingdecisions on information derived from another local service node; e.g.,one which operates off the same parent/source node. Where that otherlocal node is experiencing exceptionally high demand for HD services(and hence placing a larger load on the first parent/source node), thenthe second local service node might be configured to switch to a secondparent node, thereby reducing demand on the first parent node.

Myriad other schemes for utilizing data between individual nodes of thenetwork in conjunction with the methods of the present invention will berealized by those of ordinary skill. Note also that the operation of therules engine of the present invention may be coordinated or evenintegrated with the functionality provided by the rules engine describedin the U.S. patent application Ser. No. 10/881,979 filed Jun. 29, 2004,cited above.

It will be recognized that while certain aspects of the invention aredescribed in terms of a specific sequence of steps of a method, thesedescriptions are only illustrative of the broader methods of theinvention, and may be modified as required by the particularapplication. Certain steps may be rendered unnecessary or optional undercertain circumstances. Additionally, certain steps or functionality maybe added to the disclosed embodiments, or the order of performance oftwo or more steps permuted. All such variations are considered to beencompassed within the invention disclosed and claimed herein.

While the above detailed description has shown, described, and pointedout novel features of the invention as applied to various embodiments,it will be understood that various omissions, substitutions, and changesin the form and details of the device or process illustrated may be madeby those skilled in the art without departing from the invention. Theforegoing description is of the best mode presently contemplated ofcarrying out the invention. This description is in no way meant to belimiting, but rather should be taken as illustrative of the generalprinciples of the invention. The scope of the invention should bedetermined with reference to the claims.

1.-34. (canceled)
 35. A method of bandwidth management in a contentdistribution network having a plurality of consumer premises equipment(CPE), said plurality of CPE being configured to receive standarddefinition (SD) and high definition (HD) content, said methodcomprising: scheduling said SD content simultaneously to first andsecond user channels, said first user channel being associated with afirst physical channel for delivering SD content; mapping said seconduser channel to said first physical channel for delivering SD content;receiving a request for HD content from one or more individual ones ofsaid plurality of said CPE; and in response to receiving said request,re-mapping said second user channel to a second physical channel fordelivery of said HD content to said one or more individual ones of saidplurality of CPE.
 36. The method of claim 35, wherein said requestcomprises said one or more individual ones of said plurality of CPEtuning to said second user channel.
 37. The method of claim 36, whereinsaid method further comprises: receiving a request to tune away fromsaid second user channel for delivery of said HD content from at leastone of said one or more individual ones of said plurality of CPE; andselectively re-mapping said second user channel to said first physicalchannel for delivery of SD content.
 38. The method of claim 35, wherein:said network comprises a switched broadcast delivery network; and saidfirst and said second physical channels each comprise one or morequadrature amplitude modulated (QAM) channels.
 39. A method of bandwidthmanagement in a content delivery network having a plurality of consumerpremises equipment (CPE), said method comprising: identifying a firstand a second program content associated with a session and beingdelivered to at least one of said plurality of CPE, said first andsecond program content being provided sequentially and separated by oneor more short duration events; evaluating one or more criteriaassociated with said at least one of said plurality of CPE to determinean expectation of said at least one of said plurality of CPE continuingto require said session for viewing of said second program content uponcompletion of said first program content; and based at least in part onsaid evaluation, determining whether to selectively tear down saidsession after completion of said first program content, or to continueto provide said session for delivery of said one or more short durationevents and said second program content.
 40. The method of claim 39,wherein said selectively tearing down said session occurs prior to thestart of said second program.
 41. The method of claim 39, wherein saidselectively tearing down said session occurs after completion of saidone or more short duration events.
 42. The method of claim 39, whereinsaid session comprises a high-definition (HD) session.
 43. The method ofclaim 42, wherein said HD session is replaced with a standard-definition(SD) simulcast after said selective tear down occurs.
 44. The method ofclaim 39, wherein said one or more short duration events comprise one ormore of: (i) an advertisement, (ii) a promotion, and/or (iii) anintroduction.
 45. The method of claim 39, wherein said one or morecriteria is/are related to the total number of programs provided in saidsession.
 46. The method of claim 39, wherein said one or more criteriais/are related to the genre of said programs provided in said session.47. A method of bandwidth management in a content distribution networkcomprising a plurality of consumer premises equipment (CPE), said methodcomprising: receiving a request for a particular program from one ormore individual ones of said plurality of CPE; determining that said oneor more individual ones of said plurality of CPE are within a subset ofsaid plurality of CPE associated with a service level; and when it isdetermined that said one or more individual ones of said plurality ofCPE are within said subset, enabling said one or more individual ones ofsaid plurality of CPE to access a multiplex, said multiplex comprising aplurality of substantially identical time-shifted copies of saidparticular program.
 48. The method of claim 47, wherein durations ofrespective ones of time shifts between each of said individual ones ofsaid plurality of said time-shifted identical copies of said program areidentical.
 49. The method of claim 47, wherein said service levelcomprises a service level entitling said ones of said subset to accessto high-definition (HD) content.
 50. The method of claim 49, wherein aduration of a time shift associated with one or more of saidtime-shifted copies is based at least in part on one or more of: (i) thetotal running time of said program, and/or (ii) a bandwidth associatedwith the provision of a single HD stream.
 51. The method of claim 47,wherein said request comprises said one or more individual ones of saidplurality of CPE tuning to a logical channel associated with saidparticular content.
 52. The method of claim 51, wherein said methodfurther comprises selectively tearing down said multiplex, saidselectively tearing down being based at least in part on all of said oneor more individual ones of said plurality of CPE tuning away from saidlogical channel associated with said particular content.
 53. Networkapparatus configured for use within a network having a plurality ofconsumer premises equipment (CPE) associated therewith, said apparatuscomprising: one or more interfaces, said interfaces configured toprovide first and second content streams to said plurality CPE via saidnetwork; a storage entity configured to store rubric logic; andprocessing logic operative to: receive a channel switching patternassociated with an individual one of said plurality of CPE; evaluatesaid channel switching pattern using said rubric logic; and based atleast on said evaluation, optimize said provision of said first andsecond content streams; wherein said optimization comprises one or moreof: (i) setting up said first content streams, and (ii) tearing downsaid second content streams.
 54. The network apparatus of claim 53,wherein said rubric logic comprises one or more of: (i) an algorithm,and (ii) a database.
 55. The network apparatus of claim 53, wherein saidevaluation of said switching pattern using said rubric logic comprisesidentifying at least one user behavior.
 56. The network apparatus ofclaim 55, wherein: said user behavior comprises rapid channel hopping;and said first content streams are associated with logical channelsinvolved in said rapid channel hopping.